1. Field of the Invention
This invention relates to an exposure apparatus, and to a method of making a micro-device using the exposure apparatus, when a micro-device (for example, a semiconductor element of a semiconductor device, a liquid crystal display element, an imaging element (e.g., a CCD), a thin film magnetic head, or the like) is fabricated by a photolithography process.
2. Description of Related Art
Conventionally, exposure apparatus for fabricating a semiconductor element are provided with an illumination device and a projection optical system. A circuit pattern formed on a mask is projected and transferred onto a photosensitive substrate, such as a wafer on which a photo-resist is coated, via the projection optical system.
U.S. Pat. No. 5,737,137 discloses an exposure apparatus using an ELV ray (extreme ultraviolet ray) in the soft X-ray region of approximately 5 nm-21 nm. In order to transfer finer micro patterns onto a photosensitive substrate, it is necessary to sufficiently satisfy stricter illumination conditions in the illumination device of the exposure apparatus. However, adjusting mechanisms that sufficiently satisfy strict illumination conditions are not known.
Therefore, one object of the invention is to provide a method of fabricating an improved micro-device by exposure of a finer micro pattern, and to provide an exposure apparatus that is highly capable of satisfying strict illumination conditions.
In order to accomplish the above-mentioned and/or other objects, according to one aspect of the invention, an exposure apparatus includes a projection system, an illumination optical system, a drive system, first and second illumination adjustment mechanisms and first and second telecentricity adjustment mechanisms. The projection system has an exposure field that is decentered with respect to an optical axis in order to project a pattern formed on a mask onto a photosensitive substrate. The illumination optical system forms an illumination field at a position on the mask which is decentered with respect to the optical axis of the projection system in order to guide a light beam for exposure to the exposure field. The drive system relatively moves the mask and the photosensitive substrate along a specified scanning exposure direction with respect to the projection system. The first illumination adjustment mechanism adjusts an illumination characteristic, along the scanning exposure direction, in one of: (a) the exposure field of the projection system which is formed on the photosensitive substrate, and (b) an illumination field which is formed on the mask. The second illumination adjustment mechanism adjusts an illumination characteristic, in a direction crossing the scanning exposure direction, in one of: (a) the exposure field of the projection system which is formed on the photosensitive substrate, and (b) the illumination field which is formed on the mask. The first telecentricity adjustment mechanism applies an oblique component to telecentricity in one of: (a) the exposure field of the projection system and (b) the illumination field formed on the mask. The second telecentricity adjustment mechanism adjusts telecentricity relative to the optical axis in one of: (a) the exposure field of the projection system formed on the photosensitive substrate and (b) the illumination field formed on the mask.
According to one aspect of the invention, the illumination optical system forms an arcuate illumination field on the mask in the direction crossing the scanning exposure direction.
According to another aspect of the invention, the first illumination adjustment mechanism applies an illumination distribution component that is oblique relative to the scanning exposure direction, and the second illumination adjustment mechanism applies an illumination distribution component that is oblique relative to the direction crossing the scanning exposure direction.
According to another aspect of the invention, the illumination optical system includes a plurality of illumination optical components, and the first and second illumination adjustment mechanisms move or incline at least some similar ones of the illumination optical components among the plurality of illumination optical components in mutually different directions, or respectively move or incline mutually different ones of the illumination optical components which are different from each other.
According to another aspect of the invention, the first telecentricity adjustment mechanism adjusts an illumination optical component which is different from an illumination optical component adjusted by the first and second illumination adjustment mechanisms, and the second telecentricity adjustment mechanism adjusts an illumination optical component which is different from an illumination optical component which is adjusted by the first telecentricity adjustment mechanism, or the same illumination optical component that is adjusted by the first telecentricity adjustment mechanism.
According to another aspect of the invention, the illumination optical system includes a plurality of reflective components, and the first and second illumination adjustment mechanisms, and the first and second telecentricity adjustment mechanisms respectively adjust the position of at least some of the reflective components of the illumination optical system.
According to another aspect of the invention, the first and second illumination adjustment mechanisms incline a common reflective member about mutually different axes of rotation, or move the common reflective component in mutually different directions.
According to another aspect of the invention, the first and second telecentricity adjustment mechanisms move the common reflective member in mutually different directions.
According to another aspect of the invention, the first and second illumination adjustment mechanisms adjust a reflective component that is different from a reflective component that is adjusted by the first and second telecentricity adjustment mechanisms.
According to another aspect of the invention, the illumination optical system includes: a light source that provides the light beam; a reflective optical integrator that makes uniform an illumination distribution on the photosensitive substrate or the mask; and a light guiding optical system, arranged between the light source and the reflective optical integrator, and that guides the light beam from the light source to the reflective optical integrator.
According to another aspect of the invention, an illumination condition changing mechanism is further provided, which changes an illumination condition in an illumination field formed on the mask, or an illumination condition in the exposure field of the projection system formed on the photosensitive substrate. Furthermore, the first and second illumination adjustment mechanisms, and the first and second telecentricity adjustment mechanisms perform their respective adjustments according to a change of the illumination condition affected by the illumination condition changing mechanism.
Another aspect of the invention pertains to a method of fabricating a micro-device using the exposure apparatus, and includes the steps of: illuminating the mask utilizing the illumination optical system; and exposing an image of the pattern of the mask onto the photosensitive substrate utilizing the projection system.
Another aspect of the invention pertains to an exposure apparatus having an illumination optical system, a projection system, a drive system, and first and second telecentricity adjustment mechanisms. The illumination optical system includes a plurality of reflective components for illumination, and guides a light beam for exposure to a mask. The projection system projects a pattern of the mask onto a photosensitive substrate. The drive system relatively moves the photosensitive substrate and the mask with respect to the projection system along a specified scanning exposure direction. The first telecentricity adjustment mechanism applies an oblique component to telecentricity in one of: (a) an exposure field of the projection system which is formed on the photosensitive substrate and (b) an illumination field formed on the mask. The second telecentricity adjustment mechanism adjusts telecentricity relative to the optical axis in one of: (a) the exposure field of the projection system which is formed on the photosensitive substrate and (b) the illumination field formed on the mask. The first and second telecentricity adjustment mechanisms respectively adjust at least some of the reflective components of the illumination optical system.
According to another aspect of the invention, the second telecentricity adjustment mechanism moves the reflective component that is adjusted by the first telecentricity adjustment mechanism in a direction different from a direction in which the reflective component is moved by the first telecentricity adjustment mechanism, or moves a reflective component that is different from the reflective component that is adjusted by the first telecentricity adjustment mechanism.
According to another aspect of the invention, the illumination optical system includes: a light source that provides the light beam; a reflective integrator which makes uniform an illumination distribution on the photosensitive substrate or the mask; and a light guiding optical system, arranged between the light source and the reflective integrator, and that guides the light beam from the light source to the reflective integrator.
According to another aspect of the invention, the projection system has an exposure field which is decentered with respect to the optical axis, and the illumination optical system forms an illumination field at a position on the mask which is decentered with respect to the optical axis of the projection system in order to guide the light beam for exposure to the exposure field by using a plurality of reflective components.
According to another aspect of the invention, an illumination condition changing mechanism is further provided, and changes an illumination condition in an illumination field formed on the mask, or an illumination condition in the exposure field of the projection system formed on the photosensitive substrate. Additionally, the first and second telecentricity adjustment mechanisms perform the respective adjustments according to the change of the illumination condition made by the illumination condition changing mechanism.
Another aspect of the invention pertains to a method of fabricating a micro-device using the exposure apparatus.